Kinase Family NKF1

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Kinase Classification: Group Other: Family NKF1

This family was originally defined in the human kinome paper as New Kinase Family 1. It is found in most animals, but no member is well characterized.


NKF1 is found in most animals and choanoflagellates. Three members are found in human: SBK, and SgK069 and SgK110

Rough Draft of Sgk069/SgK110 History

These two genes are highly similar and found as a tandem duplication in human. This synteny is conserved at least through to the lizard, Anolis. The Xenopus assembly is ambiguous, and neither gene has a clear ortholog in fish (fish do have several additional NKF1 family members). The current (Aug 2011) human genome annotation classifies SgK110 and SgK069 as a single gene (SBK2) due to one EST that spans the two ORFs.

Domain Structure

The kinase domain occupies most of the protein, with short and variable extensions on both termini.


SBK (SH3-Binding domain Kinase) was found as an interaction partner of one of the Fas SH3 domains, and as a brain-enriched transcript in rat [1]. It was recently shown to be a survival factor for ovarian carcinoma cell line and to be dysregulatd in cancers [2]. Cosmic reports two cancer mutations in SBK1 and none in SBK2 (SgK069/SgK110) from large-scale resequencing. A Xenopus homolog (Pk9.7, also called SBK1, though probably not the true ortholog) is reportedly expressed only in blastula and gastrula stages of development [3] and is implicated in control of microtubules.

Of the two Drosophila homologs, CG11221 is uncharacterized, and CG4595 has some high throughput data. It is expressed selectively in the brain. The worm gene, C01C4.3 is also uncharacterized


  1. Nara K, Akasako Y, Matsuda Y, Fukazawa Y, Iwashita S, Kataoka M, and Nagai Y. Cloning and characterization of a novel serine/threonine protein kinase gene expressed predominantly in developing brain. Eur J Biochem. 2001 May;268(9):2642-51. DOI:10.1046/j.1432-1327.2001.02157.x | PubMed ID:11322885 | HubMed [Nara]
  2. Wang P, Guo J, Wang F, Shi T, and Ma D. Human SBK1 is dysregulated in multiple cancers and promotes survival of ovary cancer SK-OV-3 cells. Mol Biol Rep. 2011 Jun;38(5):3551-9. DOI:10.1007/s11033-010-0465-8 | PubMed ID:21104019 | HubMed [Wang]
  3. Snape AM and Smith JC. Regulation of embryonic cell division by a Xenopus gastrula-specific protein kinase. EMBO J. 1996 Sep 2;15(17):4556-65. PubMed ID:8887547 | HubMed [Snape]
All Medline abstracts: PubMed | HubMed